1. Field of the Invention
The present invention relates to a vehicle transmission including gear trains with a plurality of shift stages which can selectively be established; a shift drum provided in the outer with at least one circumferentially extending lead groove; drive means for rotatably driving the shift drum; a shift fork which has a shift pin slidably engaged with the lead groove and switches the established states of the gear trains with gear stages according to the operation resulting from the turning of the shift drum.
2. Description of Background Art
Such a vehicle transmission is known from e.g. patent document 1, in which, to alternatively establish gear trains with a plurality of shift stages, shift positions corresponding to the respective gear trains are set so as to be spaced from each other in the circumferential direction of the shift drum.
However, in the vehicle transmission configured as disclosed in Japanese Utility Model Publication No. 62-8683, to increase the shift positions set on the shift drum, the increased diameter of the shift drum enlarges the transmission and the significant change of the shape of a lead groove increases design manhours.